The pads are used in air coolers to cool the air but make it more humid. Is it possible to use copper / aluminum coils instead of pads to get cold and dry air?

  • $\begingroup$ Can you provide photos/links/generally more information? It's difficult to know exactly what you're talking about... $\endgroup$ Commented Jun 18, 2018 at 21:37
  • $\begingroup$ am talking about Evaporative cooler like this: breezair.com.au/wp-content/uploads/2016/01/… $\endgroup$ Commented Jun 18, 2018 at 22:02
  • $\begingroup$ vote to close. insufficient prior research, unclear what OP is asking. $\endgroup$ Commented Jun 19, 2018 at 4:29

2 Answers 2


Reverse cycle air conditioners, heat pumps by another name, are closed system coolers whereby heat is transferred form one side of a divide to another, ie from inside a room to outside the building, when cooling.

Evaporative air coolers operate on a totally different principle. Water is evaporated and dispersed into the air to cool the air by absorbing heat. In doing so they increase the humidity of the air inside the room. Because of this, such coolers are not suited to environments with humid air, such as tropical regions and coastal regions. They are best suited to areas with dry air, such as deserts.

If the pads of an evaporative air cooler were to be replaced with a coil, as you ask, there is nothing to evaporate. The only way for such a system to work is to turn the evaporative air cooler into a refrigerative air conditioner (also known as a reverse cycle air condition or a heat pump). This defeats the purpose of having an evaporative air cooler. You may as well just acquire a reverse cycle air conditioner.

  • $\begingroup$ "If the pads of an evaporative air cooler were to be replaced with a coil, as you ask, there is nothing to evaporate." why!? why the water inside coils can't be evaporating? $\endgroup$ Commented Jun 19, 2018 at 17:40
  • $\begingroup$ Sure it can, theoretically, but then the whole cycle changes, as described above... in practical use, however, it wouldn’t all evaporate when inside a pipe, which is why other fluids are used as refrigerant most commonly $\endgroup$ Commented Jun 19, 2018 at 21:56

Copper or aluminum coils are used not in evaporative coolers (which add humidity); they are used in heat pump-style coolers that have compressors, pumps and freon refrigerant (and subtract humidity). These two types of coolers are completely different in how they work and their cooling components cannot be interchanged.

  • $\begingroup$ i know copper coils are used in air conditioner, but why is not possible(or possible) to use them in evaporative coolers instead of pads(wood wool or honeycomb), in order to prevent adding humidity. when air hit the circulated water in the copper coils, the air exist become cooler with no humidity change $\endgroup$ Commented Jun 19, 2018 at 1:28
  • $\begingroup$ OK- I understand you now. Here's an explanation: when you cool down air with cold refrigerant running through coils, the moisture in the air condenses onto the coils if they are below the dew point temperature, and it runs off them for disposal. The same thing would happen if you ran cold water through the coils. the problem then becomes this: how do you make that water cold in the first place? One way to do it is by spraying water into the airflow (this is more or less what an evaporative cooler does) then the water cools down by evaporation . on to next comment- $\endgroup$ Commented Jun 19, 2018 at 1:39
  • $\begingroup$ ... and extracts heat from the air both because of the water's heat capacity and because of its heat of evaporation. But unless the water feed is ice-cold, the cooling process will be dominated by the heat of evaporation and not by the coldness of the feed water. Therefore: since heat transfer is better if the water flow simply runs through the incoming air (as it does in a wetted pad) than it would be if it were inside a metal pipe, evaporative coolers use recirculated water in direct contact with the air. $\endgroup$ Commented Jun 19, 2018 at 1:44
  • $\begingroup$ thermodynamically, the evaporative cooler can be analyzed for effectiveness in comparison to a refrigeration-type cooler; this exercise can be found in any HVAC textbook. $\endgroup$ Commented Jun 19, 2018 at 1:46
  • $\begingroup$ How do you make this cold water in the first place? I do not want to make the water cold, just circulate the water in copper coils using a pump (to lift it from the tank) When the air hit the copper coils, the water absorbe the heat of air (evaporation), making the air more cooler and the rest of the water in copper coils is become more cooler $\endgroup$ Commented Jun 19, 2018 at 2:01

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